Biomass, biomass waste, and, in particular, wood waste, has been a problem for many landfill and lumbering operations. Regardless of the terminology used to describe biomass over the years (e.g., slash, chips, YUM), there are few methods that utilize biomass waste to benefit soil productivity, sequester carbon, or reduce greenhouse gas emissions.
An Oregon State University examination showed that 10 tons/acre of biochar application may increase dryland wheat yield by 26% to 33%. Dependent upon the conversion method used to obtain this biochar, approximately 33 to 80 tons of green biomass is needed. In perspective, if that biomass is removed from the forest at a rate of 10 tons/acre, one acre of treated farmland would resultantly reduce the risk of wildfire of 3 to 8 acres of forest.
In brief, charcoal and/or biochar can be a viable source of Soil Organic Matter (SOM). The Natural Resources and Conservation Service claims that an increase of 1 percent of SOM can increase soil/water potential by about 25,000 gallons/acre. Charcoal and/or biochar, when produced appropriately, can be greater than 80 percent pure carbon, making the use of this material both a way to improve soil water available to the plants and a viable way to sequester stable carbon with the alternative objective of soil improvement. This stable form of carbon will decompose on a very long time frame. Most common forms of carbon sequestration relies on vegetation growth, which may result in temporary carbon sequestration; available to future biologic decomposition.
One reason for the lack of use of biomass waste are harvest logistics and the final value of products made from biomass. Low-value biomass is often under-utilized because of the difficulty of transportation and high transportation costs thereof due to most processing facilities being located off-site from the harvesting site. In order to overcome these difficulties, wood waste is sometimes ground to reduce its volume. However, this can be expensive, harmful to the environment, and fails to reduce the amount of wood waste. Also, in some instances, grinding, chipping, and hauling the wood waste may spread problems related to insect infestation and/or negatively contribute to climate change.
When biomass has no merchantable value, a common method of biomass disposal is open air burning of residual piles. However, these methods may reduce soil productivity for years as the heat generated from such burn piles may negatively alter the soil underneath the pile. Therefore, in order to prevent such, the wood waste may alternatively be burned in fireboxes or fire pits on-site. Further, in order to reduce ash and smoke released during the incineration process, a flow of air has been used to provide an air curtain over a fire pit or firebox in which the waste is burned. For example, U.S. Pat. Nos. 4,756,258 and 5,415,113 describe portable apparatuses that may be used in air curtain incinerations. In particular, U.S. Pat. No. 4,756,258 discloses a fan and manifold assembly that can be towed to and positioned at the edge of a fire pit and U.S. Pat. No. 5,415,113 teaches a firebox, fan, and manifold assembly mounted on a support frame for transport to a desired clearing site for the incineration of waste without the need to dig a fire pit.
Further, U.S. Pat. Nos. 6,536,360 and 7,063,027 teach air-curtain fireboxes or incinerators designed to capture waste heat for useful applications. Yet even with the aforementioned advances, biomass incineration still suffers many drawbacks.
Current curtain burners offer a way to increase the speed of biomass consumption with fire and concurrently reduce the risk of wildfires. Unfortunately, current curtain burners are designed to completely consume woody biomass, ultimately and irreversibly turning the wood waste to ash. In other words, by simply eliminating biomass from a site, current curtain burners only offer a service. As such, current air curtain burners eliminate many benefits that may result from potential charcoal and/or biochar that may be produced from the biomass. Further, current air curtain burners are batch processes, requiring an operator to insert and remove material from the air curtain burners after each operational use.
Therefore, a new portable charcoal device is desired that may effectively benefit soil productivity, sequester the carbon from the wood waste into useable matter, and reduce greenhouse gas emissions during a continuous operation.